Method of making fin elements



May 27, 1952 Filed Oct. 22, 1948 M. P. P-ENN 2 SHEETSSHEET l F 3/ E W 26 I A2 34 km E a [323 14 I ,4 f l I za x L JNVENTOR.

A MN P PENN. 3 a BY y 1 Wow HIS A770E/VEV5,

May 27, 1952 M. P. PENN METHOD OF MAKING FIN-ELEMENTS 2 SHEETS-SHEET 2 Filed Oct. 22, 1948 I I, I INVENTOR.

VIN NM Patented May 27, 1952 UNITED STATES PATENT A r-rice f "Application October 22, 1948; Serial No. 55,882

.1 Claim. 1

invention relates to refrigeration and particularly .to heat exchange elements employed in rrefrigerating systems.

iAn object of my invention is to provide an improved, more efiicientand-lower cost heat transaferxdevice orv heat exchanger.

Another object of my invention is to provide an improved finnelement adapted to bemounted "-onra, fiuid-conduit-of a heat exchangerand an improved method of fabricating the fin.

s'tillgfurther object of my-invention is to pro- -vide:an improvedmethod'of making a fin element from :malleablermetaltubes each of which ele- :men-tsis providedwithspaced apart radialfin-por- -tions,. a collar portion and short tubular 'end portions forming continuations'of the collar portion thereof and extending beyond one sideof the in; portions.

A more specific object of my invention is to providea method of making afin'element by flaring end' portionsof a metallic tube to forma hollow spool member and -then deforming the spool-member to provide .a means for spacing one element from another when the elements are mounted on aconduitof .a heat exchanger.

Further advantages of the present invention will be apparent from the following description, reference 'beinghad to :the accompanying drawings, wherein .a preferred formof the present in- --vention is clearly-shown.

.In the drawings:

Fig. .1 is a. side view partly in section. and partlyiin elevation ofa portion of a fluid conducting conduit of a heat exchanger having in elements constructed .inaccordance .with the present invention thereon;

Fig-.2 is an endyiew of the device-shown in -Eis. .1;

Fig.3 .is-a view of a tubular piece :of malleable :metal from which the finvelements on the heat exchanger conduit shown in Figs. land "2' are fabricated;

"Fig. Alisa view 'partly. in sectionand partly in elevation showing forming members incontact 'with the tube and ready to perform one step in the method of making-fin elements of the present invention;

Fig. 5 is a view similar to Fig.4 and shows the forming members-movedto completethe first step in the method of making the'fin elements;

Fig. 6 is a sectional 'view of other forming mem- .bers showing a further step inthe present-meth- 0d; and Y T'ig. 7 "isa'view similar to Fig: 6 showing movement of the forming members in completing -the .method of providing the'finished finelements.

Referring to the drawings, for illustrating .-my invention, I have-shown .inFig. 1 thereof a portion of a metal conduit [9 of a heat transfer device-or heat exchangersuch, :for example,-as 'acondenser or evaporator employed in refrigerating and the like systems. Conduit Hlxhas-a plurality of-fin elementsi 'I- mounted thereon for increasing the heat tr-ansf er surface thereof. The elements Il may be formedof anysuitable metal and are, ashereinafter ,described, fabricated from aluminum tubes while-theconduit may --be' formed of any suitable .metal such as copper or steel. Finelementsl I- may be secured .in intimate thermal contact with the outer surface:of=-conduit I0 in any-suitable mannerasis conventional-in the "art. Each element llihas ea 'pair of spaced apart circular in portions 12 formed integral with and extending radially from a collar portion I4. Each element-ll also..has short; tubular extensions 5 concentric witha-nd formingcontinuations of the collar portion l4 .at-the-sideofeach =fin portionwl2. 'Ilheextensions l5 on the one side of fin element .1 l, opposite the sides thereon joinedto or integral-with the collar portionv l 4, serve to a space the fin portions I 2 of the elements the proper :or equalwdistance apart when a plurality of the elements .H are placed adjacent one another on the conduit. 1.0. These :short extendingtubular portions 15 are ,of utmost importance since they eliminate the use of expensive rake or rack like-tools or-dies for spacing fin elements on a conduit prior to or at the -time the finelementsaresecured thereto. The fin elements I I may be secured-tothe conduit =l0 .by brazing-the same thereto, expanding the wall -of conduit l0 outwardly against the-collar portion 1 4 of the elements or .in anyother .wellknown andconventional manner. Ordinarily .a completed heat exchanger will include aplura'lity o'f-lengths of finnedtubing or conduit of the'ty'pe shown in Fig. 1. either connected in series .orfin parallel.

I ;have illustrated, in the presently disclosed method of fabricating fin elements, "only those parts of the mechanisms or machineswhicha'ct "directly upon the elementsfor the sake of simplicity and since the "manner" of causing move- 'mentand operation offparts of such machines is "well-known to thoseskilled in the art; In -Fig$3 ofthedrawings I show a tube of malleable-metal; such, for example, as copper onalu- "minum'capable'of bein'g'rolled out'without cracki-ng" orbreaking and%or of flowing underpressure.

Due to the high heat conducting and malleability properties of aluminum or aluminum alloys I employ a tube I1 of aluminum metal which is adapted to be deformed by my method to provide one of the tubular fin elements shown in Fig. 1. Tube I1 is preferably of substantially pure aluminum known to the trade as commercial aluminum and consisting of 0.2% copper, 1.0% iron and silicon, .05% manganese, .10% zinc, .05% each of other alloys and the remainder pure aluminum.

Prior to starting the fabricating method a portion of the outer wall surface of tube |1 along the center thereof is confined by walls of a hole or opening 23 provided in a plate 24. Plate 24 is composed of two half parts disposed in end-toend relationship with their ends abutting one another at the line indicated by the reference character 25 (see Figs. 4 and '1). Each half part of plate 24 has a circular notch cut inwardly from their abutting ends extending throughout an arc of 180. Thus when the half parts of plate 24 are brought into end-to-end engagement the notches form walls of the opening or round hole 23. The half parts of plate 24 are bolted or otherwise suitably clamped together with walls of hole 23 tightly engaging tube I1 and thereafter a plunger 26, formed on a round movable forming member 21,, is inserted into the opening of the tube. In this manner both the inner and outer wall surfaces of tube l1 along a portion thereof centrally of its ends are confined. After confining these wall surfaces of tube H, by plate 24 and plunger 26, the tube is ready to be deformed. Before describing the operation of deforming tube |1 it is desired to point out that a second or lower movable forming member 28 is also associated with the tube and that this member 28 has a hole 29 therein for the reception of plunger 26. Member 21 has a conical surface 3| intermediate the enlarged portion thereof and the plunger portion 26. Member 28 is also provided with a conical surface 32 at its upper end. The smaller end portions of the conical surfaces 3| and 32 engage end portions of the inner wall of tube I1.

Movement of members 21 and 28 toward one another and toward plate 24 causes the conical surfaces 3| and 32 thereon to be forced into tube [1 and the walls adjacent the ends of the tube are flared outwardly relative to the confined central wall portion thereof. Both members 21 and 28 have a shaft 34 attached thereto and secured to a pressing device, air cylinders or any other suitable means for moving the members 21 and 28 in a direction toward one another. If desired the forming members 21 and 28 may also be rotated simultaneously with their movement toward one another. Thus when the members 21 and 28 are moved toward one another to apply pressure to both ends of the tube, the end portions thereof are progressively moved or fiared outwardly as indicated by the final position of the forming members 21 and 28 illustrated in Fig. of the drawings. It will be noted by reference to Fig. 5 that the plunger 26 on member 21 has moved into the hole 29 in member 28 and that the tube H has, by virtue of its being centrally confined and by having its ends flared outwardly,

been formed into a hollow spool-like member 36 including the collar portion I4 and the two spaced apart fin portions l2. After this step in the method has been completed the movable members 21 and 28 are separated and the plunger 26 withdrawn from the member 28 and moved outwardly of the spool member or element 36. The

members 21 and 28 are then moved out of vertical alignment with the spool member 36 and other forming or die members moved into vertical alignment therewith.

Two opposed round die or forming members 4| and 42 (see Fig. 6) are moved into engagement with the ends of the flared fin portions |2 of spool member 36. The upper die member 4| is movable toward the lower member 42 and has a plunger 43 depending therefrom. Plunger 43 is moved into the collar portion M of member 36, so as to take the place of plunger 26 in confining the inner wall surface of the collar, and extends into a hole 44 provided in the die member 42. The plunger 43 maintains the dies 4| and 42 in vertical alignment with one another while again confining the inner wall surface of collar portion I4 of the member 36. Die member 42 may be stationarily mounted. The outer wall surface of collar I4 is still confined by walls of the opening 23 in plate 24. Any suitable press or the like may be employed for moving die member 4| toward the stationary die member 42. Each die member 4| and 42 is provided with a large shallow circular counterbore 46 and an inner smaller but deeper counterbore 41 concentric with bore 46 for a purpose to now be described. As member 4| is moved downwardly from its position shown in Fig. 6 both counterbored surfaces 46 of members 4| and 42 engage the edges or ends of the outwardly flared portions |2 of spool shaped element or member 36 and force the portions l2 to move in a further outward direction until they are substantially perpendicular to the axis of the collar portion l4 of member 36. Continued downward movement of member 4| to the position thereof shown in Fig. 7 of the drawings brings the face portions of the die members 4| and 42, outwardly of the counterbores 46, into 1 1 close relationship to the upper and lower surface of plate 24. In this position the forming dies 4| and 42 confine substantially all portions of member 36 except the portions adjacent the deep counterbores 41. It is to be understood that the depth of the counterbores 46 is less than the wall thickness of portions |2 of member 36 so that when the die members 4! and 42 are forced into the position illustrated in Fig. 7, with their face portions tightly engaging the plate 24, force applied to the member 36 and particularly the fin portions |2 thereof compresses the portions 2 and this compression causes the metal thereof to flow into the counterbores or cavities 41. Flow of a part of the material of fin portions |2 of element 36 into the cavities created by the counterbores 41 forms the tubular end portions 49 (see Fig. 7) concentric with and forming continuations of the collar portion M of the fin element. These portions 49 extend a short distance beyond one side of the fin portions |2 of element and provide on each element means for spacing adjacent fin portions |2 of the separate elements H a desired distance apart when the ele ments are strung or mounted on conduit H). To remove the double fin element H from the machine or press, die members 4| and 42 are moved outwardly away from one another and thereafter the two parts of plate 24 are separated from one another on the line indicated by the reference character 25. Another tube |1 may then be placed in the machine or press, confined and deformed as described.

From the foregoing it should 'be apparent that I have, in addition to providing an improved fin element for use on conduits of heat exchangers,

also provided a novel method of making or fabrieating the fin. By deforming a short length of malleable metal tubing and utilizing all the material thereof for essential portions of a fin element I reduce waste to a minimum and eliminate the necessity of performing further steps to provide the finished element. My invention permits the production of many fin elements in a short period of time and thus reduces the cost of finning a conduit to thereby lower the manufacturing cost of a heat exchanger or heat transfer device.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adapted, as may come within the scope of the claims which follow.

What is claimed is as follows:

The method of making fin elements adapted I to be mounted on a conduit of a heat exchanger which consists in, confining the inner and outer wall surfaces of a malleable metal tube along a part centrally of the ends thereof, flaring the ends of the tube beyond said confined surfaces outwardly to form the same into a hollow substantially spool-shaped member having an intermediate collar portion and conical end portions, and then in a single die set performing the operations of moving said conical end portions of said member into perpendicular relationship to the axis of said collar portion while still confining said wall surfaces to form a pair of axially spaced apart radially extending fins, confining at least a part of the edges of said fins to restrict radial outward flow of the material thereof and simul- 6 taneously confining all wall portions of said member except those at the base of said fins on the sides thereof opposite the sides joined to said, collar portion, and applying pressure to said member to cause the material thereof to flow at said unconfined portions axially relative to and concentric with said collar portion to form a short axial extension thereof beyond each fin.

MELVIN P. PENN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 736,551 Roemer Aug. 18, 1903 1,046,138 Babbit et al. Dec. 3, 1912 1,297,141 Gibbons Mar. 11, 1919 1,420,970 Cornell, Jr June 27, 1922 1,521,864 Broido Jan. 6, 1925 1,791,887 Davis et al Feb. 10, 1931 1,922,351 Brown Aug. 15, 1933 2,070,539 Muhleisen Feb. 9, 1937 FOREIGN PATENTS Number Country Date 733 Switzerland Mar. 15, 1889 19,886 Great Britain Sept. 6, 1906 294,687 Great Britain July 30, 1928 343,398 Germany Nov. 1, 1921 399,995 Great Britain Oct. 19, 1933 502,579 Great Britain Mar. 21, 1939 593,824 Great Britain Oct. 27, 1947 

